content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2011, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
   * Other names may be trademarks of their respective owners.]
   *
   * --------------
   * XYDataset.java
   * --------------
   * (C) Copyright 2000-2008, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes (from 18-Sep-2001)
   * --------------------------
   * 18-Sep-2001 : Added standard header and fixed DOS encoding problem (DG);
   * 15-Oct-2001 : Moved to a new package (com.jrefinery.data.*) (DG);
   * 22-Oct-2001 : Renamed DataSource.java --> Dataset.java etc. (DG);
   * 17-Nov-2001 : Now extends SeriesDataset (DG);
   * 15-Jul-2004 : Switched getX() with getXValue() and getY() with
   *               getYValue() (DG);
   * 29-Jul-2004 : Added getDomainOrder() method (DG);
   * 18-Aug-2004 : Moved from org.jfree.data --> org.jfree.data.xy (DG);
   *
   */
  
  package org.jfree.data.xy;
  
  import org.jfree.data.DomainOrder;
  import org.jfree.data.general.SeriesDataset;
  
  /**
   * An interface through which data in the form of (x, y) items can be accessed.
   */
  public interface XYDataset extends SeriesDataset {
  
      /**
       * Returns the order of the domain (or X) values returned by the dataset.
       *
       * @return The order (never <code>null</code>).
       */
      public DomainOrder getDomainOrder();
  
      /**
       * Returns the number of items in a series.
       * <br><br>
       * It is recommended that classes that implement this method should throw
       * an <code>IllegalArgumentException</code> if the <code>series</code>
       * argument is outside the specified range.
       *
       * @param series  the series index (in the range <code>0</code> to
       *     <code>getSeriesCount() - 1</code>).
       *
       * @return The item count.
       */
      public int getItemCount(int series);
  
      /**
       * Returns the x-value for an item within a series.  The x-values may or
       * may not be returned in ascending order, that is up to the class
       * implementing the interface.
       *
       * @param series  the series index (in the range <code>0</code> to
       *     <code>getSeriesCount() - 1</code>).
       * @param item  the item index (in the range <code>0</code> to
       *     <code>getItemCount(series)</code>).
       *
       * @return The x-value (never <code>null</code>).
       */
      public Number getX(int series, int item);
  
      /**
       * Returns the x-value for an item within a series.
       *
       * @param series  the series index (in the range <code>0</code> to
       *     <code>getSeriesCount() - 1</code>).
       * @param item  the item index (in the range <code>0</code> to
       *     <code>getItemCount(series)</code>).
       *
       * @return The x-value.
       */
      public double getXValue(int series, int item);
  
      /**
       * Returns the y-value for an item within a series.
       *
       * @param series  the series index (in the range <code>0</code> to
       *     <code>getSeriesCount() - 1</code>).
       * @param item  the item index (in the range <code>0</code> to
       *     <code>getItemCount(series)</code>).
       *
       * @return The y-value (possibly <code>null</code>).
       */
      public Number getY(int series, int item);
  
      /**
       * Returns the y-value (as a double primitive) for an item within a series.
       *
       * @param series  the series index (in the range <code>0</code> to
       *     <code>getSeriesCount() - 1</code>).
       * @param item  the item index (in the range <code>0</code> to
       *     <code>getItemCount(series)</code>).
       *
       * @return The y-value.
       */
      public double getYValue(int series, int item);
  
  }
  